Trinh Thi Bich Nhu was three years old when she lost the use of her legs. For the next 25 years she felt useless, until she met a swimming coach who helped transform her life. Now she's one of Vietnam's Paralympic athletes training for Rio.

A short, sharp "chirrup" of a whistle and she's off, arms windmilling through the water, a trail of bubbles in her wake. She keeps going, full pelt, for two hours at a time, popping her head up only to hear advice from her coach before ducking back back down.

The pool, the coach, the friends swimming alongside her, even the scooter she rides to training - there was a time when she would never have thought all this could be possible.

When she was three, Nhu developed a fever, and her cousin had the flu. Fearing the infection would spread, her father separated the children, taking her cousin to receive treatment first. By the time he came back for Nhu, it was too late. She had polio.

"After I got the fever, my legs still looked normal but were immobile. My mum had to give me a cushion to prop me up... I couldn't move," she says.

Living in a rural part of Vietnam, life closed in for Nhu - she felt useless. "I stayed at home with my mum to help her with odd chores, and couldn't do anything else. I felt isolated."

Image caption
Nhu with her coach, Cuong Guong

Then, in 2010, when she was in her 20s, a friend introduced her to a swimming coach, Dong Quoc Cuong (or Coach Cuong), in Ho Chi Minh City. "I told him that I would only swim for fun and that I wouldn't train... the swimsuit put me off." She balked at the idea of wearing one, saying it was for what she called "normal people".

Nhu wouldn't even let her mother touch her legs - she was very sensitive about their appearance and didn't feel she could swim in something so revealing. She felt "awkward and disabled" and remembers sitting there, unresponsive, for 15 whole minutes.

But Coach Cuong was quite insistent: "He told me that everybody here was disabled like me." Later he tried a gentler approach: "Please try and swim," he said. "If you can do it, great. If not, no problem."

After a few strokes of doggy-paddle, he told her she had "lots of potential" and she found herself winning medals within the year. "When I win, it feels like I'm flying in the clouds," she says.

Since then she has travelled the world as part of the Vietnamese national team, usually competing in the 50m butterfly, 100m breaststroke and 200m medley.

She doesn't know how many medals she's won, but some triumphs stand out. Her proudest moment was winning silver in the Glasgow IPC Swimming World Championships in 2015. "Coming from a small country, I didn't dare to think I would win anything."

Nhu's exhilaration comes from both representing her country, as well as the freedom she has gained since finding the sport. A wheelchair gets her around short distances but she used to rely on lifts from friends to get to training. With the prize money from her first medals, she was able to buy a modified scooter.

She laughs as she tells of her terror riding it for the first time. After buying it, she left it in the garage for a week, not quite sure who'd help her onto it. But Coach Cuong soon called and told her she had to get to training because long breaks aren't good. "So I dived straight in," she says, "and got on the bike and rode slowly, slowly - just twisted the accelerator very lightly." Now she navigates the swarms of bikes on Ho Chi Minh City's streets with ease.

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Nhu (left) and her friends on their scooters

Nhu is hoping for further sporting success - making a living in Vietnam can be hard if you're disabled, she says. For now she has a gruelling schedule as she prepares for upcoming competitions.

Her days start early with swimming, gym training and physical therapy. And in the evenings she watches clips of her hero, Olympic gold-medal-winning swimmer Michael Phelps, to pick up tips. "His arms are so long and his movements are very beautiful, I try to copy them myself."

Presiding over her programme is the same Dong Quoc Cuong who's been by the water's edge since the beginning, six years ago. They have a strong relationship which extends outside the pool. "He is more like my mentor," says Nhu.

"He taught me things about life, how to live, how to behave with friends and other people.

"In the past I thought that because I was disabled, no one would love me." Now she's surrounded by a close group of teammates, other Paralympic athletes who live together, train together, and take care of each other. She says there is a greater understanding between them because they are in a similar situation.

Nhu thinks she has at least five more years swimming at this level - this year's Paralympics in Brazil are giving her an added incentive. She's also planning to get married after the games, and following that, she'd like to open a shop.

Out of the pool, at the peak of Vietnam's midday heat, there's a moment to have lunch and catch her breath. The sun glistens on the water, and there's a quiet chatter of close friends as Nhu and her teammates discuss the day's training and their evening plans.

There is a sense of home-coming for Nhu that's more than just winning medals. From feeling useless and being teased as a country girl in the big city, to feeling exposed when wearing a swimsuit, she has faced her share of obstacles.

But now, "Swimming has become my passion. Every time I get into the water, I feel... relaxed," she says.

"When I'm on the ground, I am a weak person... but when I'm in the water I can move wherever I want to. I feel powerful."